Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this disclosure and are not admitted to be prior art by inclusion in this section.
Video is made up of a sequence of images called frames, and perhaps associated audio. During playback, the sequence of frames can be displayed in succession, generally at a constant rate, together with the audio.
Digital video refers to video that is represented in a digital format. With digital video, each frame is a digital image. Each digital image is represented as a grid of pixels, each pixel having particular color values (such as RGB color values). A collection of digital video is often stored as a video file.
Encoding and compression techniques may be used to efficiently store digital video. According to some encoding standards, such as those specified by the Motion Picture Expert Group (MPEG), digital video may be stored as a series of reference frames and incremental frames, each representing a change relative to a corresponding reference frame. As a result, an encoded video file based on an MPEG standard typically begins with a reference frame, to allow subsequent incremental frames to be determined on the basis of the reference frame.
Television-broadcasting systems typically include a network of devices arranged to receive video from one or more of a variety of sources and output video to an air-chain system for broadcast (e.g., over the air according to a number of different standards). One such source can be a news production system (NPS) that may output a particular type of video, namely a news program which may be a combination of live or pre-recorded video, either of which may be dynamically modified with digital video effects (DVE).
An NPS can include a video playout module for playing pre-recorded video. Typically, pre-recorded video is stored as an encoded video file. As a result, a selected encoded video file can generally be played back, starting from an initial reference frame. Playback then ends either upon reaching a final frame of the encoded video file, or upon occurrence of some interruption event.
In preparing a news program for broadcast, a producer may select a sequence of particular encoded video files to be played in accordance with a schedule. In some cases, the producer may wish to include only a subset of a particular encoded video file, as opposed to the entire file. In such case, the producer may cause a second encoded video file to be generated, where the second video file is a subset of the first video file.